It's optional for any content provider. It's not required but what's the big issue? Google has already said they pay for this type of service to other providers. If company's a willing to pay to reach more customers on limited plans, then let them.
FYI: when you make a claim (even one that is obviously correct), the burden is on the claimant to support his or her claim. The reader has no burden to do their work for them.
I would consider his comment to be common knowledge and courtesy as well as posting etiquette.
If you are going to make a claim then it is on your to provide the support to such claim. Otherwise, you can't really argue with someone that claims otherwise.
it helps. Also its been blogged about on here by Karl before.
